In the normal mode, these devices are functionally equivalent to the 'F244 and 'BCT244 octal buffers. The test circuitry can be activated by the TAP to take snapshot samples of the data appearing at the device terminals or to perform a self test on the boundary-test cells. Activating the TAP in normal mode does not affect the functional operation of the SCOPETM octal buffers.

In the test mode, the normal operation of the SCOPETM octal buffers is inhibited and the test circuitry is enabled to observe and control the I/O boundary of the device. When enabled, the test circuitry can perform boundary-scan test operations, as described in IEEE Standard 1149.1-1990.